Answer: Dorothea can make 13 bracelets.
Step-by-step explanation: If Dorothea has 260cm of strings, she should cut the string accordingly to set aside the strings. Cutting 260cm of 20cm length each would be the same as doing 260 divided by 20. If you do the math (mentally or using a calculator), you would get 13 pieces of strings, meaning Dorothea can make 13 bracelets. Hope this helped!